Pigment and process of making same.



llNiTnp STATES PATENT FFICE.

PlGll/IENT AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No.

719,415, dated February 3, 1903.

Application filed May 26, 1902. Serial No. 109,091- (No specimens.)

To (1 whom it may concern.-

Be it known that 1, WILLIAM J. ARMBRUS- TER, a citizen of the UnitedStates, residing at St. Louis, State of Missouri, have invented certainnew and useful Improvements in Pigments and Processes of Making theSame, of which the following is a specification.

My invention has relation to improvements in processes of manufacturingpigments and in the product resulting therefrom; and it consists,respectively, in the novel steps and in the novel product more fully setforth in the specification and pointed outin the claims.

The composition consists of an intimate mixture of precipitated bariumsulfate, zinc sulfid, and barium carbonate in various proportions, saidproportions depending on the relative proportions of the respectivesolutions constituting the mixtures from which the salts areprecipitated. In the preparation of my compound I employ mixtures ofsolutions of zinc sulfate, a carbonate of an alkali metal, and bariumsulfid, the precipitates being formed in the order of the chemicalaffinities between the several bases and acids. The proportions in whichthe several solutions shall be mixed resolve themselves into simplestoicheiometric problems; but the following are cited as specificexamples of my process, the product in each case being the same.

I prepare a solution of one molecular equivalent of zinc sulfate, onemolecular equivalent of sodium carbonate, and two molecular equivalentsof barium sulfid, bringing the several solutions intimately together,when from the resulting mixture there will be precipitated one molecularequivalent of barium sulfate, one molecular equivalent of zinc sulfid,and one molecular equivalent of barium carbonate, leaving one molecularequivalent of sodium sulfid in solution, as better apparent from thefollowing chemical reactions:

It was stated above that the constituent parts of the compoundprecipitate will be formed in the order of the chemical affinitiesbetween the several bases and acids, and since the affinity betweenbarium and sulfuric acid is greater than that between the same base andcarbonic acid it follows that one molecular equivalent of barium sulfateand one equivalent of zinc sulfid will be formed simultaneouslyaccording to the following reaction:

ZnSOH-fZBaS:BaSOH-ZnS-l-BaS.

The molecule of barium sulfid immediately reacts on the sodium carbonatepresent,forming the resulting precipitate of barium carbonate andleaving the sodium sultid in solution, thus:

Of course practically the several precipitates form approximately at onetime, though chemically the reactions follow the sequence outlinedabove.

The foregoing example contemplates a mixture of one molecular equivalentof zinc sulfate, one of sodium carbonate, and two of barium sulfid; butobviously I need not limit myself to these proportions, as these may bedeparted from without in any wise affecting the nature or spirit of myinvention. As an example of such departure I may take one molecularequivalent of zinc sulfate, two equivalents of sodium carbonate, andthree equivalents of barium sulfid, thus producing one equivalent ofbarium sulfate, one equivalent of zinc sulfid, two equivalents of bariumcarbonate, leaving two equivalents of sodium sulfid in solution, as perfollowing reaction:

As another example of such departure I may mix the equivalents accordingto the following reaction:

While in the foregoing I employ sodium carbonate, it is apparent that Imay avail myself of any of its chemical equivalents, such as ammoniumcarbonate or potassium carbonate, the reactions being in all respectssimilar to those outlined above. Whatever be the nature of the chemicalemployed in determining what shall be the relative quantities of theseveral ingredients to produce the precipitate on a commercial scale theusual stoicheiometric problem presents itself, a problem based on theatomic Weights of the several elements composing the molecule by whichthe reaction is effected. Thus in practice, and referring specificallyto the first example above cited, I take an aqueous solution of onehundred and sixty-one (161) pounds of zinc sulfate, one hundred and six(106) pounds of sodium carbonate,'and three hundred and thirty-eight(338) pounds of barium sulfid and bring the solutions together in anysuitable manner, when a compound precipitate of five hundred andtwenty-seven (527) pounds will result and seventy-eight (78) pounds ofsodium sulfid will remain in solution. This precipitate will contain twohundred and thirty-three (233) pounds of barium sulfate, ninety-seven(97) pounds of zinc sulfid, and one hundred and ninety-seven (197)pounds of barium carbonate. The sodium-sulfid solution is separated fromthe precipitate by filtration and subjected to suitable evap0ration,which crystallizing with nine molecules of Water forms two hundred andforty (240) pounds of sodium-sulfid crystals. The precipitate maybe'washed before recovery.

I am aware that there is in use a pigment of zinc sulfid and bariumsulfate in various proportions known as lithopone; but this I do notclaim, for while precipitated barium sulfate as a pigment has the virtueof permanency, yet it has no body or opacity when mixed with oil andbeing almost if not altogether transparent if used alone. Precipitatedbarium carbonate while also classed as a transparent pigment when usedin oil, yet

has somewhat more body or opacity in oil than precipitated bariumsulfate, is also a very permanent pigment, and has a highlyattractivequality in that it usually forms in a more amorphous or less crystallinebody than the sulfate, and, moreover, it is unctuous and smoother. Inactual practice it is found that when precipitated barium carbonate issubstituted for precipitated barium sulfate, either wholly or in part,when combined with zinc and lead whites the resultant compound pigmentworks smootherand finer, grinds easier in oil, flows more readily fromthe brush, and spreads easier under the brush.

As an example of the successive precipitation of the individual productscomposing the final mixture the following reactions may be cited:

2BaS+Na OO =BaCO +Na S+BaS; Na S+BaS+ZnSO :BaSOfi-ZnS-l-Nafi,

the resulting barium carbonate, barium sulfate, and zinc sulfid beingsubsequently and intimately mixed by any of the well-known mechanicalmethods.

Having described my invention, what I claim is 1. The process of makingpigment consisting of mixing solutions of zinc sulfate, a carbonate ofan alkali metal, and barium sulfid, and recovering the resultingprecipitates, substantially as set forth.

2. The process of making pigment consisting of mixing solutions of zincsulfate, so-' dium carbonate and barium sulfid, and recovering theresulting precipitates, substantially as set forth.

3. The process of making pigment which consists in mixing solutions ofmolecular equivalents of zinc sulfate, a carbonate of an alkali metal,and barium sulfid, and recovering the resulting precipitates,substantially as set forth.

4. The process of making pigment which consists in mixing solutions ofmolecular equivalents of zinc sulfate, sodium carbonate, and bariumsulfid, and recovering the resulting precipitates, substantially as setforth.

5. The process of making pigment which consists in mixing solutions ofapproximately one hundred'and sixty-one pounds of zinc sulfate, onehundred and six pounds of sodium carbonate, and three hundred andthirty-eight pounds of barium sulfid, and recovering the resultingprecipitates, substantially as set forth.

6. A pigment composed of a mixture of barium sulfate, zinc sulfid andbarium carbonate, in substantially the proportions specified.

7. A pigment composed of a precipitate of barium sulfate, zinc sulfid,and barium carbonate, in substantially the proportions specified.

8. A pigment composed of precipitated bariu m sulfate and zinc sulfid,intimately mixed with a precipitate of barium carbonate, substantiallyas set forth.

9. A pigment comprising a mixture of the precipitates of two hundred andthirty-three parts by weight of barium sulfate, ninetyseven parts ofzinc sulfid, and one hundred and ninety-seven parts of barium carbonate,substantially as set forth.

In testimony whereof I affix my signature in presence of two witnesses.

WILLIAM J. ARMBRUSTER.

Witnesses:

EMIL STAREK, G. L. BELFRY.

